I read one time here about a person being upgraded with 2 cabins. But, since you are on a waitlist, if 2 category 8's become available, I can't imagine that they would give you a complementary upgrade. With the waitlist, I really think you will have to pay.
After the 60 day mark for my trip, cabin categories that had been listed as unavailable suddenly become available. I really do think people cancel. If the move up is really important, I'd call each morning and each afternoon for the week prior and around the 60 day mark to check availability. The opened cabins might be picked up by someone else calling before they ever look at the wait list.